Chords

Play three or more notes together and they fuse into a chord - a single harmonic unit with a name. What makes a chord a chord isn't the key you're in: it's the pattern of intervals stacked up from a root. A major chord is a root, a major third, and a perfect fifth - in any key, on any root.

Pick a root and hold a chord button to hear and see it on the keys. Or play your own notes - the readout names the chord, tells you which inversion you've voiced, and offers any other names the same notes could carry. Play something that isn't a chord and it'll tell you that too.

The same notes, more than one name

Harmony is often ambiguous. The notes C-E-G-A are a C major 6th or an A minor 7th depending on which note you hear as the root - and the lowest note (the bass) usually decides. Some chords are perfectly symmetrical: an augmented triad or a diminished 7th has no single root at all, so the page shows every reading. Which one is "correct" comes down to the key - a later concept.

Inversions

A chord keeps its identity no matter which note is at the bottom. Put a note other than the root in the bass and you have an inversion - C major with E in the bass is still C major (written C/E). The chord name doesn't change; the inversion is reported alongside it.

Spelling stays neutral here

You'll notice a black-key chord shows two names, like C♯ major / D♭ major, and its tones keep both spellings. A chord does imply a precise spelling - a D♭ major chord is truly D♭-F-A♭ - but choosing between sharps and flats needs a key, and keys are a concept still to come. So a C♯ major chord shows its middle note as plain F rather than E♯. When the Scales and Key Signatures concepts land, that's exactly the gap they'll fill.

How chords are built: stacked thirds

Almost every chord is built by stacking thirds. Start on a root, skip a step to add the third, skip again for the fifth, again for the seventh, and so on. Musicians write this as a formula of scale degrees: 1 3 5 is a triad, 1 3 5 7 a seventh chord. Apply the formula 1 3 5 7 in C and you get C-E-G-B, a C major 7th. The same formula in any key gives the same kind of chord on a different root.

Two, three, four notes

Chords are grouped by how many distinct notes they contain. A dyad is two notes - any interval counts, and the most common one is the bare fifth, the power chord. A triad is three, the staple of pop and rock. A quadad is four, usually a triad with a seventh added, the bread and butter of richer harmony. You can keep stacking past four into the extensions, but the more distinct notes you pile on, the more they tend to clash, which is why simple songs use simple chords and jazz reaches for the dense ones.

The three families

However many qualities exist, almost all of them fall into three families defined by the third and the seventh. A major third with a major seventh is the major family: stable and bright. A minor third puts a chord in the minor family: stable but darker. A major third with a minor seventh is the dominant family: tense and restless, built to resolve. Most other chords are these three coloured by added or altered notes, which is why even jazz musicians treat every chord as major, minor, or dominant at heart.

What this page leaves out

To keep things honest about scope: the buttons always play chords in root position (inversions are recognised, not offered as buttons), and recognition covers triads, sevenths, suspended and power chords, sixths, and the common extensions and alterations (9ths, 11ths, 13ths, add9, 6/9, altered dominants). It deliberately doesn't cover quartal harmony (chords built from stacked fourths), polychords, deliberate tone clusters, slash chords with a non-chord-tone bass, multiply-altered jazz voicings, or anything microtonal. And which chords belong to a given key - the diatonic chords, Roman numerals, ii-V-I - is its own concept, still to come.